Conduit construction



Feb. 25,1930. L. M. KING 1,748,134

GONDUIT CONSTRUCTION Filed March 8, 1928 2 Sheets-Sheet 1 qua f f INVE/YTQE 400052 l7. KING t g4 M M HAS arrgexvsx Feb. 25, 1930. KlNG 1748,13!

' CONDUIT CONSTRUCTION Filed March 8, .1928 2 Sheets-Sheet 2 INVENTOE LOCH/E'L /7. KING HIS ATTORNEY Patented Feb. 25, 1930 PATENT OFFICE LooH IEL M. KING, or ALAMELDA, CALIFORNIA ooN'DU'I'r CONSTRUCTION applicants filed March'S, 1928. Serial No. 259,934.

' My invention relates tothe construction of reenforced concrete conduits, and particu larly to under-water tubes for vehicular and railway trafiic, but it is also applicable to a ueducts sewers and other conduits. Its

.broad purpose is to provide a practical construction using pre-cast reenforced concrete (sections.

An object of my invention is to provide a lo conduit of uniform strengt Another object of my invention is to provide a joint .for conduit sections which may, easlly be formed under water.

' Still another object of my invention is to provide asubstantia'lly tightconduit joint.

, A further object ofmyinvention is to provide a conduit construction which is low 111 "cost in comparison with other types.

I My invention possesses other objects and valuable features, some of which will be set forth in the following description of my invention which is illustrated in the drawings forming part of thespecification. It is to be understood that I do not limit myself to the showing made by the said description and drawings, as I may ad'optvarying forms of my invention within the scope of the claims.

For illustration I will describe my inven- Y tion as embodied in subway "construction of i which there are two types in general use. The

older ofthese involves the use of a shield, forced forward by jacks and backed by com-,

I pressed air, behind which'the workers oper-- ate. As the shield advances cast iron rings are bolted in place, and the inside is then covered with a layer of concrete. The operationis expensive and hazardous.

' The other method comprises digging a trench for the subway, laying a riveted steel tube in the trench and then pouring concrete into the trench to cover the tube and format permanent monolithic structure. While this construction offers certain advantages over the first method, the amount of concrete used is enormous, and the cost is high. I

In the constructionof subways, as in any major engineering problem, cost is inevitably the determining factor. The saving which would be effected were it possible to use a uniform tube of reenforced concrete of the proper section to withstand the stresses is obvious, and accordingly it has been often proposed to pre-cast a tube of the proper dimensions in sections, lay them like steel tubes in a trench, and back-fill over the completed subways. This has not been done, because no joint which has hitherto been proposed for joining such sections was at once watertight, adequate to Withstand the stresses which would be set up in it, and easy enough of construction to be practical. To provide a joint which meets these requirements is to reduce by as much as 30 to 40 per cent the cost of an engineering operation in which the expenditures run into millions of dollars, and

the plane of section being indicated by the line 2-2 of Fig. 1. The tremie pipe for pouring the outer seal is shown at the left of the figure and the beginning of the outer seal appears at the bottom of the figure.

Figs. 3 and 4 are sectional views on a larger scale, taken on the line 3-3 of Fig. 2 and showing the joint respectively partly completed and finished.

Broadly considered my invention comprises conduit sections formed with encircling, preferably quadrilateral flanges spaced slightly from their ends; and provided with counterbores into which extend longitudinal reenforcing bars embedded in the Walls of the sections. These sections are placed in position on grade piers with the ends abutting,

and an outer seal is poured about the joint,

. vided for attaching a form or diaphragm to the vertical edges of the flanges. A convenient attaching means is a length of steel sheet piling 11 embedded in the flange with the tongue edge 12 projecting. Between the flange and the end of the section aflange collar 13 encircles the tube, so as to form an annular keyway around theend of the section. r

I/Vithin the ends of the section are counterbores 14 extending back into the tube. The exact length of the counterbores ls not important, but they may conveniently termi nate in the annular faces 16 about as far from the end ofthe section as the collar 7. The

longitudinal reenforcing bars 17 extend through the face 16 and into thecounterbore.

The. sectons are also provided with outer reinforcing bars'18 whichend a short distance from the end faces 19 of the tu besections. Annular grooves 21 are formed within the counterbores of each section preferably under the collar 13, in order to avoid too great a reduction of cross-section of the tube.

i A trench is'excavated to receive thesubway, and grade piers 22 are set for the tube to rest upon. A pair of piers is provided to receive each flange and between the piers of each pair is placed a diaphragm 23, which may be built of riveted plates, and which extends from the grade level down to and slightly into the sub-grade 24.

Bulkheads are fixed in the ends of the tube sections, which are floated into position and then sunk into place on the grade piers. In doing this the faces 19 are brought into as close approximation as practical, but a crack will be left between the faces which may be several inches in width. Where this is the case it is caulked with wooden chocks 26 and a gasket or belt 27 is then passed around the joint, and drawn tight by bolts 28 bearing against angles 29 secured to the belt. 7

The material of the belt may be rubber or canvas belting, or it may be a steel band. In the case of the closing joint, formed where the last section is placed, it maybe advisable to allow several feet between the ends of the sections to facilitate their handling. In this case the belt would be a steel ring, and the chocks 26 would be omitted.

The steel forms 10, preferably semi-cylindrical, withinterlocks 32 to engage the sheet piling 11 are next slid into place to close the space between the flanges. The forms ex- 7 flanges 11.

tend to or. silghtly below the subgrade, and i the space between the flanges thus becomes a compartment, closed except at the top, into which a concrete seal 33 is poured by means of a tremie pipe 34;. Any slight leakage due to failure of the forms to close exactly may be blocked by the use of sand bags.

Pouring the seal entirely from one side is advantageous in that thejconcrete rises simultaneously from both sides and the formation of voidsis mlnlin-ized. The cross-section of the compartment is ample to allow Pouring continues until the seal is level with the tops of the flanges. It will be noted that the seal, when set, surrounds and is firmly keyed to the sections.

The outer seal being completed, the inside of the joint is next formed. Caulking 36is driven into the-crack between the faces 19, V

and pipes 37 are passed through the caulking and left projecting into the bore of the tube to be used later.

The reinforcing bars 17. were either bent back out of the way. as shown in Fig; 3 or cut off within the counterbore, so as not to V V interfere when the sections were being placed.

They are now straighten'ed or extensions are Welded on so that the reinforcing bars of each section extendsubstantially the entire length of the adjoning counter-cores; Circumferential reinforcing 38 is placed, and temporary forms are applied within which the inner seal 39 is formed. The longitudinal rein-- forcement within the seal is thus the combined reinforcement of the two adjacent-sections, stressed in pure tension, overlapping, and anchored by andintothe seal from both directions. The lower part ofthe seal is first poured; then the upper part is forced in under pressure. Like the outerseal, the inner seal ls keye'd to, the tube sections, the grooves 21 serving this purpose.

The final stage in the formationof the joint is forcing a grouting, preferably of neat cement, through the tubes 37, andinto the space between the faces 19 of the section ends. .This is done underv heavy pressure, andthe grouting enters any interstices which mayIhave been left in the formation of the seals, and practically eliminates leakage at the joint. Such leakage is slight in any event, as the bond between the seals and the tube sections is long and the leakage path tor tuous. One of the advantages of the curved plate form 10 is its ability to adjust itself to variations in the spacing of the anchor A stress analysis of a joint soformed shows it to have'a strength at least as great as the body of the tube. There are, of

course, many minor modifications of struc- I the strength.

Y struction in particular.

' limited to underwater construction, although ture which may be made Without impairing Forexample, box forms may be used instead of diaphragms to conflnethe outer seal between the gradepiers, the forms between the flanges may be bolted in place instead of slipped over sheet piling, and

7 methods of caulking may be varied at'will.

The joint described, however is adequate, andlow in cost; and is applicable to structures designed for a variety of uses. There is a wide field for its usein outfall sewercon- Neither is its use byfthe use of tremie concrete it gives the greatest durability obtainable in structures of this class.

I claim- 1. A conduit comprising abutted sections, each section having an integral flange disposed thereabout, and a concrete seal surrounding the ends of the sections between the flan es b u I 2. A conduit comprising abutted sections,

each section having a collar and an integral flange disposed thereabout, and a concrete seal surrounding the ends of the sections between the flanges and interlocking with the collars. t 7 I 3. A conduit comprising abutted sections,

. each section having a flange disposed thereabout, a" retaining form connecting the flanges, and a concrete seal surrounding the ends of the sections and filling the chamber between the flanges and the form.

4. A conduit comprising abutted sections,

' each section having a quadrilateral flange and a concrete seal surrounding disposed thereabout, anchor'flanges arranged in the edges of the section flanges, aretaining form secured between the anchor flanges, the ends of the sections and filling the chamber between the flanges and the form. v

5. A conduit comprising abuttedsections, each section having a quadrilateral flange disposed thereabout, sheet piling embedded in the section flanges, a curved metal form secured between the piling, and a concrete seal surrounding the endsof the sections and filling the chamber between the flanges and the form.

' 1 6. A conduit comprising abutted sections,

each section having a collar and a quadrilateral flange disposed thereabout, a curved metal form connecting the flanges, and a concrete seal surrounding the ends of the sections between the form and the flanges and interlocked with the collars.

7 A conduit comprising abutted sections,

each section'having a flange disposed thereabout, a form connected to said flanges, a band encircling the juncture of said sections, and a" concrete seal disposed in the space between the flanges and form and band.

8. A conduit comprising abutted sections,

' each section having a quadrilateral flange flanges on opposite vertical edges thereof,

means for closing the space between the lower edges of the flanges, and a concrete seal surrounding the ends of the sections in the space between the flanges and forms and closing means.

9. A conduit comprising abutted sections, each section having a flange disposed thereabout, a form connected to said flanges, a concrete seal surrounding the ends of the sections between the flanges and form, and means for interlocking the seal with the section ends.

10. A conduit comprising abutted sections, each section having an integral flange disposed thereabout, a concrete seal surrounding the ends of the sections between the flanges and means for interlocking the seal with the section ends.

11.. A conduit comprising abutted sections the end of each section having a flange on the outside and a counterbore on the inside, a concrete ring surrounding the abutting ends of the sections between the flanges and a concrete ring filling the counterbores.

12. A conduit comprising abutted sections, the end of each section having a flange on the outside and a counterbore on the inside, a concrete ring surrounding the abutting ends of the sections between the flanges, a concrete ring filling the counterbores, and means for interlocking the concrete rings with the section ends.

13. A conduit comprising abutted sections, the end of each section having a flange on the outside and a counterbore on the inside, a concrete ring surrounding the abutting ends of the sectionsbetween the flanges, a concrete ring filling the counterbores, means for interlocking the concrete rings with the section ends, and reenforcing bars extending from each section into the counterbore filling ring.

14. A conduit comprising abutted sections, each section having a counterbore on the inside, a concrete ring surrounding the abutting ends of the sections, and a concrete ring filling the counterbores.

15. A conduit comprising abutted sections, each section having a counterbore on the inside, a concrete ring surrounding the abutting ends of the sections, a concrete ring filling the counterbores, and means for interlocking the concrete rings with the section ends.

In testimony whereof, I have hereunto set 

